Leica APO-SUMMICRON-SL 28mm F/2 ASPH.

Wide-angle prime lens • Digital era

Abbreviations

APO The lens features apochromatic optical design.
ASPH. The lens incorporates aspherical elements.

Production details

Announced:February 2021
Production type:Mass production
Production status: In production
Order No.:11183 - black anodized
Original name:LEICA APO-SUMMICRON-SL 1:2/28 ASPH.
System:Leica L (2015)

Features highlight

Fast
APO
3
Bi-ASPH
8
AD
IF
9 blades
Dual
STM
Dual Syncro Drive
DP/WR
FC
E67
filters

Specification

Optical design
Focal length:28mm
Speed:F/2
Maximum format:35mm full frame
Mount and Flange focal distance:Leica L [20mm]
Diagonal angle of view:75.4°
Lens construction:13 elements - 10 groups
3 Bi-ASPH, 8 AD
Internal focusing (IF)
Diaphragm mechanism
Diaphragm type:Automatic
Aperture control:None; the aperture is controlled from the camera
Number of blades:9 (nine)
Focusing
Closest focusing distance:0.24m
Maximum magnification ratio:1:5 at the closest focusing distance
Focusing modes:Autofocus, manual focus
Manual focus control:Focusing ring
Autofocus motor:Dual Stepping motor (Dual Syncro Drive)
Focus mode selector:None; focusing mode is set from the camera
Manual focus override in autofocus mode:Determined by the camera
Optical Image Stabilizer (OIS)
Built-in OIS:-
Physical characteristics
Weight:700g
Maximum diameter x Length:⌀73×102mm
Weather sealing:Dust-proof and water-resistant barrel
AquaDura coating:Front and rear elements
Accessories
Filters:Screw-type 67mm
Lens hood:Bayonet-type (petal-shaped)
Lens caps:16045 (front)
16064 (rear)
Teleconverters:Not available

*) Source of data: Manufacturer's technical data.

35mm equivalent focal length and speed (on APS-C cameras)

In terms of FoV & DoF
Camera series [Crop factor] Focal length SpeedMax MR Dia. angle of view
Leica T/TL/CL APS-C [1.53x] 42.8mm F/3.11:3.27 53.6°

Manufacturer description #1

February 18, 2021. With the APO-Summicron-SL 28 f/2 ASPH., Leica Camera presents yet another high-performance wide-angle lens for the Leica SL-System. The APO-Summicron-SL 28 f/2 ASPH. is the latest addition to the ever-expanding APO-Summicron-SL series that includes a lens range renowned for its top-level optical performance and extremely fast and reliable autofocus.

Following the existing focal lengths of 35, 50, 75 and 90 mm, the APO-Summicron-SL 28 f/2 ASPH. is the first true wide-angle prime lens in this series, making the APO-Summicron-SL 28 f/2 ASPH. especially suitable for reportage, interior and architectural photography. Its maximum aperture can be used without any loss of image quality and offers additional creative possibilities through the exquisite balance of sharp subjects and lovely soft background blur. Thanks to the L-Mount standard, the APO-Summicron-SL 28 f/2 ASPH. is equally compatible with cameras made by other partners of the L-Mount Alliance that have been equipped with the Leica-developed lens mount.

As is universally appreciated with all Leica lenses, the fastest aperture delivers maximum performance. As a result, reducing the aperture is only necessary for compositional and creative purposes. Leica lenses always deliver an exceptional quality of natural skin tones, soft transitions into creamy bokeh, contrast-rich details and edge-to-edge sharpness across a distortion-free image. Yet the APO-Summicron-SL 28 f/2 ASPH. is further distinguished by its apochromatic correction, which is a notable feature in a lens of this focal length, and its six aspherical lens surfaces. To ensure the optimal correction of chromatic aberrations, the majority of the grouped lens elements feature anomalous partial dispersion and are made of high-quality specialized glass. The end result is a wide-angle lens that delivers impeccable images complete with the “Leica Look” to help realize a creative vision in any avenue of photography.

The autofocus drive of all APO-Summicron-SL lenses utilizes extremely robust and high-performance stepping motors with DSD® (Dual Syncro Drive™). This enables the AF to travel the entire focusing range in around 250 milliseconds. Leica Camera also takes an innovative approach to manual focusing technology, including an entirely new manual focus ring construction in the form of an embedded ring magnet with alternating north-south polarization. When the ring is turned, the magnetic field changes its polarity. A sensor monitors the status of the magnetic field and sends the data to the main processor. The drive then shifts the lens to the corresponding focusing position based on the angle of rotation and the rotational speed, delivering even faster and more precise manual focusing to match the lens’s quick and accurate autofocus.

Both the construction and design of the cutting-edge APO-Summicron-SL series represent the next step forward in the development of lenses for the Leica SL-System. New, extremely precise manufacturing methods and measuring technologies have been developed specifically for the production of these lenses, resulting in more compact dimensions as well as truly outstanding imaging performance. In the construction of the APO-Summicron-SL lenses, particular attention has been paid to the prevention of stray light and reflections by applying a high-quality coating to the lens surfaces. Thanks to their effective sealing against dust, moisture, and water spray, as well as the Aquadura coating of the exposed lens surfaces, these extremely durable lenses can be used in nearly any weather condition without any cause for concern. The ever-expanding portfolio of Leica SL lenses are built to withstand the elements and the test of time, matching its futureproof counterparts in the SL2 and SL2-S with their rugged construction and continuing firmware development ensuring a long service life.

Manufacturer description #2

The APO-Summicron-SL 28 f/2 ASPH. combines a classic wide-angle focal length with state-of-the-art technology. Its angle of view provides a good overview, both for interior and exterior scenes, without any undue distortion of the perspective.

The ability to accentuate the focal plane at open aperture without loss of quality gives the photographer a far greater scope of creative possibilities. This makes the APO-Summicron-SL 28 f/2 ASPH. not just a universal lens, but one that produces truly extraordinary compositions.

The autofocus system shared by the Summicron-SL lenses is fast, precise, and nearly silent. Their outstanding AF performance figures are thanks to the autofocus drive unit they both utilize. These are limited only by the mass of the glass elements moved when focusing; the speed of moving from infinity to the closest focusing distance. In order to preserve the compact dimensions of the lenses, the integration of these components must be perfectly optimized within all design constraints.

Specialists from the areas of optical engineering, mechanical engineering and electronics worked together as an interdisciplinary team on the development of a unique lens concept based on double internal focusing. This system, comprising two especially light focusing lenses, allows the construction of particularly small and compact drive systems. While being able to work within tight space constraints, the drive motors used must maintain peak performance in all situations to be chosen for such a cutting-edge camera system.

Several contrast measurements at various focusing positions must be made before the correct direction for focusing can be determined and followed by precise focusing. In this procedure, the focusing lens elements must be moved rapidly in accordance with the speed specifications of the contrast AF system. This requires a dynamic drive system without any room for error.

In the Summicron-SL lenses, the drive units installed are extremely powerful and robust stepping motors with Dual Syncro Drive™. Thanks to these, the entire focusing range can be traveled completely in fractions of a second. This means that the Summicron-SL lenses achieve values that are among the best in the full-frame system segment in terms of speed, precision, and operating noise.

With a maximum aperture of f/2, the SL-Summicron lenses are significantly more compact than even faster lenses, but still allow photographers to work with similar depth of field. The reason for this is contrast: the area of highest contrast is incredibly sharp, while zones with lower contrast are unsharp or beautifully blurred.

In the case of SL-Summicron lenses, this difference in contrast is considerably higher than that of conventional lenses: sharply focused objects show much higher contrast than objects that are out of focus. This means that objects “pop” more distinctly out of the foreground or background and more effectively isolate the subject. This creates a three-dimensional visual effect with very impressive depth.

In the construction of the Summicron-SL lenses, particular attention has been paid to the prevention of stray light and reflections. The optimization of the optical and mechanical design was carried out in elaborate simulations before the construction of the first prototype lenses. Unavoidable reflections are reduced to the lowest possible level by high-quality optical coatings of the lens surfaces.

The focusing and aperture setting functions of a SL-Summicron lens are based on a multitude of control systems and mathematical operations. The demands on the electronics are particularly high in the case of the dual-synchro drive focusing system.

The two autonomous focusing units must be moved in perfect synchronization and positioning data must be analyzed at a very high sampling rate and passed on to the camera. Here, the communication with the camera is so fast that there is no perceptible delay. These are the primary preconditions for fast and precise contrast autofocus.

The aperture is driven by a stepping motor. Here, a special micro-step control system ensures precise and fast movements with minimized vibration.

SL-Summicron Lenses feature a totally new manual focusing ring construction concept. In this concept, a ring magnet with alternating north-south magnetization is embedded in the manual focusing ring. The magnetic field changes its polarity when the ring is turned. A sensor monitors the status of the magnetic field and sends the data to the main processor. The drive then shifts the lens to the corresponding focusing position on the basis of the angle of rotation and the rotational speed.

The construction of the manual focus ring guarantees reliable sealing against dust and water spray, provides protection against impacts and other mechanical stresses, and prevents focusing inaccuracies as a consequence of temperature fluctuations. Even after years of use, the manual focus ring of a SL-Summicron lens maintains a smooth action without play and homogeneous focusing.

The consistently compact dimensions, low weight, and the excellent grip and feel of the SL-Summicron lenses are particularly impressive when shooting. Thanks to the almost identical design of the Summicron-SL lenses, each one handles nearly identically and the center of gravity remains largely the same. This means that the camera always lies perfectly in the hand and makes working from a tripod much easier.

What makes the APO-Summicron-SL 28 f/2 ASPH. so special is an optical system comprising of 13 lens elements produced with unique expertise and the latest manufacturing technology by Leica. Of these, three elements with six aspherical surfaces correct monochromatic aberration, while eight elements manufactured from specially formulated, high-quality glass types ensure chromatic correction throughout the entire focusing range.

Only the particular optical property of these glass types, known as anomalous partial dispersion, makes it possible to compensate for chromatic aberrations with such perfection. As a consequence of this, even highlights in images remain almost completely free of color fringing.

From the editor

The manufacturer states that the lens features 13 elements in 10 groups, and it corresponds to the "LENS CUT" on page 2 of the Technical Data. However, the "TECHNICAL DRAWING", which can also be found on the same page of the Technical Data, shows 14 elements in 10 groups: the focusing group located closer to the focal plane consists of 2 elements instead of 1.

Typical application

Class:

Fast full-frame wide-angle prime lens • Apochromatic optical designTravellers' choice

Apochromatic optical design

All glass elements in an optical system refract light in certain colors to a different extent. This leads to the effect that not all rays of light from a multi-colored subject are focused at a single imaging point – the result of this is chromatic aberration.

In this lens, the chromatic aberration is minimized by apochromatic correction.

A need for apochromatic correction arose with the increasing popularity of color film. Now, with high-resolution digital sensors, the need for superior control of chromatic aberrations is even more pertinent than when film changed from monochrome to color.

Travellers' choice

  • Lightweight
  • Dust-proof and water-resistant barrel
  • AquaDura coating

Genres or subjects of photography (12):

Landscapes • Cityscapes • Buildings • Interiors • Full to mid-body portraits • Photojournalism • Weddings • Parties • Carnivals • Live concerts • Street • Travel photography

Recommended slowest shutter speed when shooting static subjects handheld:

1/30th of a second

Alternatives in the Leica L system

///// Sorted by focal length and speed, in ascending order /////

Lenses with similar focal length

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35mm full frame

43.27 24 36
  • Dimensions: 36 × 24mm
  • Aspect ratio: 3:2
  • Diagonal: 43.27mm
  • Area: 864mm2

Stepping motor (Dual Syncro Drive)

The lens incorporates focusing system consisting of two autofocus drive units precisely synchronized to deliver fast and accurate autofocusing.

16045

Replacement lens cap for Leica SL E67 lenses.

16064

Replacement rear cover for Leica SL lenses.

Aspherical elements

Aspherical elements (ASPH, XA, XGM) are used in wide-angle lenses for correction of distortion and in large-aperture lenses for correction of spherical aberration, astigmatism and coma, thus ensuring excellent sharpness and contrast even at fully open aperture. The effect of the aspherical element is determined by its position within the optical formula: the more the aspherical element moves away from the aperture stop, the more it influences distortion; close to the aperture stop it can be particularly used to correct spherical aberration. Aspherical element can substitute one or several regular spherical elements to achieve similar or better optical results, which allows to develop more compact and lightweight lenses.

Use of aspherical elements has its downsides: it leads to non-uniform rendering of out-of-focus highlights. This effect usually appears as "onion-like" texture of concentric rings or "wooly-like" texture and is caused by very slight defects in the surface of aspherical element. It is difficult to predict such effect, but usually it occurs when the highlights are small enough and far enough out of focus.

Low dispersion elements

Low dispersion elements (ED, LD, SD, UD etc) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. This type of glass exhibits low refractive index, low dispersion, and exceptional partial dispersion characteristics compared to standard optical glass. Two lenses made of low dispersion glass offer almost the same performance as one fluorite lens.

Low dispersion elements

Low dispersion elements (ED, LD, SD, UD etc) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. This type of glass exhibits low refractive index, low dispersion, and exceptional partial dispersion characteristics compared to standard optical glass. Two lenses made of low dispersion glass offer almost the same performance as one fluorite lens.

Canon's Super UD, Nikon's Super ED, Pentax' Super ED, Sigma's FLD ("F" Low Dispersion), Sony' Super ED and Tamron's XLD glasses are the highest level low dispersion glasses available with extremely high light transmission. These optical glasses have a performance equal to fluorite glass.

High-refraction low-dispersion elements

High-refraction low-dispersion elements (HLD) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

High Index, High Dispersion elements

High Index, High Dispersion elements (HID) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

Anomalous partial dispersion elements

Anomalous partial dispersion elements (AD) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture.

Fluorite elements

Synthetic fluorite elements (FL) minimize chromatic aberrations and ensure excellent sharpness and contrast even at fully open aperture. Compared with optical glass, fluorite lenses have a considerably lower refraction index, low dispersion and extraordinary partial dispersion, and high transmission of infrared and ultraviolet light. They are also significantly lighter than optical glass.

According to Nikon, fluorite easily cracks and is sensitive to temperature changes that can adversely affect focusing by altering the lens' refractive index. To avoid this, Canon, as the manufacturer most widely using fluorite in its telephoto lenses, never uses fluorite in the front and rear lens elements, and the white coating is applied to the lens barrels to reflect light and prevent the lens from overheating.

Short-wavelength refractive elements

High and specialized-dispersion elements (SR) refract light with wavelengths shorter than that of blue to achieve highly precise chromatic aberration compensation. This technology also results in smaller and lighter lenses.

Blue Spectrum Refractive Optics

Organic Blue Spectrum Refractive Optics material (BR Optics) placed between convex and concave elements made from conventional optical glass provides more efficient correction of longitudinal chromatic aberrations in comparison with conventional technology.

Diffraction elements

Diffraction elements (DO, PF) cancel chromatic aberrations at various wavelengths. This technology results in smaller and lighter lenses in comparison with traditional designs with no compromise in image quality.

High refractive index elements

High refractive index elements (HR, HRI, XR etc) minimize field curvature and spherical aberration. High refractive index element can substitute one or several regular elements to achieve similar or better optical results, which allows to develop more compact and lightweight lenses.

Apodization element

Apodization element (APD) is in fact a radial gradient filter. It practically does not change the characteristics of light beam passing through its central part but absorbs the light at the periphery. It sort of softens the edges of the aperture making the transition from foreground to background zone very smooth and results in very attractive, natural looking and silky smooth bokeh.

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Image stabilizer

A technology used for reducing or even eliminating the effects of camera shake. Gyro sensors inside the lens detect camera shake and pass the data to a microcomputer. Then an image stabilization group of elements controlled by the microcomputer moves inside the lens and compensates camera shake in order to keep the image static on the imaging sensor or film.

The technology allows to increase the shutter speed by several stops and shoot handheld in such lighting conditions and at such focal lengths where without image stabilizer you have to use tripod, decrease the shutter speed and/or increase the ISO setting which can lead to blurry and noisy images.

Original name

Lens name as indicated on the lens barrel (usually on the front ring). With lenses from film era, may vary slightly from batch to batch.

Format

Format refers to the shape and size of film or image sensor.

35mm is the common name of the 36x24mm film format or image sensor format. It has an aspect ratio of 3:2, and a diagonal measurement of approximately 43mm. The name originates with the total width of the 135 film which was the primary medium of the format prior to the invention of the full frame digital SLR. Historically the 35mm format was sometimes called small format to distinguish it from the medium and large formats.

APS-C is an image sensor format approximately equivalent in size to the film negatives of 25.1x16.7mm with an aspect ratio of 3:2.

Medium format is a film format or image sensor format larger than 36x24mm (35mm) but smaller than 4x5in (large format).

Angle of view

Angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view.

As the focal length changes, the angle of view also changes. The shorter the focal length (eg 18mm), the wider the angle of view. Conversely, the longer the focal length (eg 55mm), the smaller the angle of view.

A camera's angle of view depends not only on the lens, but also on the sensor. Imaging sensors are sometimes smaller than 35mm film frame, and this causes the lens to have a narrower angle of view than with 35mm film, by a certain factor for each sensor (called the crop factor).

This website does not use the angles of view provided by lens manufacturers, but calculates them automatically by the following formula: 114.6 * arctan (21.622 / CF * FL),

where:

CF – crop-factor of a sensor,
FL – focal length of a lens.

Mount

A lens mount is an interface — mechanical and often also electrical — between a camera body and a lens.

A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock type. Modern camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body, unlike screw-threaded mounts.

Lens mounts of competing manufacturers (Canon, Nikon, Pentax, Sony etc.) are always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance can also be different.

The flange focal distance (FFD) is the distance from the mechanical rear end surface of the lens mount to the focal plane.

Lens construction

Lens construction – a specific arrangement of elements and groups that make up the optical design, including type and size of elements, type of used materials etc.

Element - an individual piece of glass which makes up one component of a photographic lens. Photographic lenses are nearly always built up of multiple such elements.

Group – a cemented together pieces of glass which form a single unit or an individual piece of glass. The advantage is that there is no glass-air surfaces between cemented together pieces of glass, which reduces reflections.

Focal length

The focal length is the factor that determines the size of the image reproduced on the focal plane, picture angle which covers the area of the subject to be photographed, depth of field, etc.

Speed

The largest opening or stop at which a lens can be used is referred to as the speed of the lens. The larger the maximum aperture is, the faster the lens is considered to be. Lenses that offer a large maximum aperture are commonly referred to as fast lenses, and lenses with smaller maximum aperture are regarded as slow.

In low-light situations, having a wider maximum aperture means that you can shoot at a faster shutter speed or work at a lower ISO, or both.

Closest focusing distance

The minimum distance from the focal plane (film or sensor) to the subject where the lens is still able to focus.

Closest working distance

The distance from the front edge of the lens to the subject at the maximum magnification.

Magnification ratio

Determines how large the subject will appear in the final image. For example, a magnification ratio of 1:1 means that the image of the subject formed on the film or sensor will be the same size as the subject in real life. For this reason, a 1:1 ratio is often called "life-size".

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Manual focus override in autofocus mode

Allows to perform final focusing manually after the camera has locked the focus automatically. Note that you don't have to switch camera and/or lens to manual focus mode.

Electronic manual focus override is performed in the following way: half-press the shutter button, wait until the camera has finished the autofocusing and then focus manually without releasing the shutter button using the focusing ring.

Fixed focus

There is no helicoid in this lens and everything is in focus from the closest focusing distance to infinity.

Internal focusing (IF)

Conventional lenses employ an all-group shifting system, in which all lens elements shift during focusing. The IF system, however, shifts only part of the optics during focusing. The advantages of the IF system are:

Manual diaphragm

The diaphragm must be stopped down manually by rotating the detent aperture ring.

Preset diaphragm

The lens has two rings, one is for pre-setting, while the other is for normal diaphragm adjustment. The first ring must be set at the desired aperture, the second ring then should be fully opened for focusing, and turned back for stop down to the pre-set value.

Semi-automatic diaphragm

The lens features spring mechanism in the diaphragm, triggered by the shutter release, which stops down the diaphragm to the pre-set value. The spring needs to be reset manually after each exposure to re-open diaphragm to its maximum value.

Automatic diaphragm

The camera automatically closes the diaphragm down during the shutter operation. On completion of the exposure, the diaphragm re-opens to its maximum value.

Fixed diaphragm

The aperture setting is fixed at F/2 on this lens, and cannot be adjusted.

Number of blades

As a general rule, the more blades that are used to create the aperture opening in the lens, the rounder the out-of-focus highlights will be.

Some lenses are designed with curved diaphragm blades, so the roundness of the aperture comes not from the number of blades, but from their shape. However, the fewer blades the diaphragm has, the more difficult it is to form a circle, regardless of rounded edges.

At maximum aperture, the opening will be circular regardless of the number of blades.

Weight

Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

Maximum diameter x Length

Excluding case or pouch, caps and other detachable accessories (lens hood, close-up adapter, tripod adapter etc.).

For lenses with collapsible design, the length is indicated for the working (retracted) state.

Weather sealing

A rubber material which is inserted in between each externally exposed part (manual focus and zoom rings, buttons, switch panels etc.) to ensure it is properly sealed against dust and moisture.

Lenses that accept front mounted filters typically do not have gaskets behind the filter mount. It is recommended to use a filter for complete weather resistance when desired.

Fluorine coating

Helps keep lenses clean by reducing the possibility of dust and dirt adhering to the lens and by facilitating cleaning should the need arise. Applied to the outer surface of the front and/or rear lens elements over multi-coatings.

Filters

Lens filters are accessories that can protect lenses from dirt and damage, enhance colors, minimize glare and reflections, and add creative effects to images.

Lens hood

A lens hood or lens shade is a device used on the end of a lens to block the sun or other light source in order to prevent glare and lens flare. Flare occurs when stray light strikes the front element of a lens and then bounces around within the lens. This stray light often comes from very bright light sources, such as the sun, bright studio lights, or a bright white background.

The geometry of the lens hood can vary from a plain cylindrical or conical section to a more complex shape, sometimes called a petal, tulip, or flower hood. This allows the lens hood to block stray light with the higher portions of the lens hood, while allowing more light into the corners of the image through the lowered portions of the hood.

Lens hoods are more prominent in long focus lenses because they have a smaller viewing angle than that of wide-angle lenses. For wide angle lenses, the length of the hood cannot be as long as those for telephoto lenses, as a longer hood would enter the wider field of view of the lens.

Lens hoods are often designed to fit onto the matching lens facing either forward, for normal use, or backwards, so that the hood may be stored with the lens without occupying much additional space. In addition, lens hoods can offer some degree of physical protection for the lens due to the hood extending farther than the lens itself.

Teleconverters

Teleconverters increase the effective focal length of lenses. They also usually maintain the closest focusing distance of lenses, thus increasing the magnification significantly. A lens combined with a teleconverter is normally smaller, lighter and cheaper than a "direct" telephoto lens of the same focal length and speed.

Teleconverters are a convenient way of enhancing telephoto capability, but it comes at a cost − reduced maximum aperture. Also, since teleconverters magnify every detail in the image, they logically also magnify residual aberrations of the lens.

Lens caps

Scratched lens surfaces can spoil the definition and contrast of even the finest lenses. Lens covers are the best and most inexpensive protection available against dust, moisture and abrasion. Safeguard lens elements - both front and rear - whenever the lens is not in use.